Observing the Beginning of Time

The expansion of the universe was apparently kicked off by a new energy field—the inflaton—less than a second after the Big Bang. The weird repulsive gravity of the inflaton is what made the Big Bang big, and it's the reason that the universe is considerably larger than an atom. Small quantum fluctuations in the inflaton field ultimately led to the formation of everything we see today, and they also left a visible imprint on the brightness of the "cosmic background radiation"—a cold light that originated in the Big Bang and still permeates the universe today. The fluctuations are evident in slight temperature differences in the background radiation that appear as slightly hot and slightly cold blotches in the sky. These blotches are the largest structures we will ever see, but they are also faithful images of the smallest things we can ever see, single elementary quanta. High-resolution images of these blotches may ultimately reveal the quantum nature of spacetime—which, for all practical purposes, would be a view of the discrete structure from which space and time emerged.